In planetary cross-roll mills, usually used for rolling tubing and pipe, the rolls with their conical external configurations or contours are so mounted or arranged on respective roll shafts that a positive transfer of torque from the roll shaft to the roll is possible in spite of the fact that a replacement of the roll is facilitated. The problem of delivery of torque to a rolling mill roll is, of course, more general and it is desirable in other rolling mill applications to be able to separate the roll from the shaft.
One of the ways in which torque has been delivered in the past, especially between a roll shaft and a mill roll has been through the use of a so-called Voith end toothing which couples the roll and the shaft for torque transfer therebetween and is hydraulically clamped through the use of a tension anchor.
In another approach the roll is fastened to the roll shaft by interfitting jaws and held together by a central screw in the roll. Both approaches have disadvantages. The Voith end tooth arrangement utilizing a hydraulically-clamped tension anchor applies high axial forces which must be absorbed in the system. The arrangement is relatively expensive because it requires hollow shafts, tension or draw bars and special rings. The hydraulic tool which is required for clamping and releasing the anchor is likewise expensive and inconvenient to use. It is also a disadvantage that the system must be frequently adjusted and in the case in which certain hydraulic devices are to be used, the draw bar or tension anchor cannot be used.
In the case of jaw-type torque transfer arrangements, the fabrication of the jaws themselves may be expensive. As a rule four uniformly-spaced jaws are employed and must be fabricated to low tolerances. They are subject to high wear and in many cases can be easily overloaded. The bending forces must be taken up by relatively short cylindrical seats which are also subject to wear and may be unduly stressed, especially as the system develops heat in use.
The disassembly of the system is difficult, especially when separation of the parts is required in the hot state. The jaws are wear parts which tend to fail with time and the heat development also affects other parts of this system.